1. Field of the Industrial application
This invention relates to a vehicle's AC generator driven by the engine of a vehicle such as an automobile, and more particularly to an improvement of the cooling technique of the AC generator.
2. Description of the Prior Art
A conventional vehicle's AC generator is as shown in FIG. 5. The AC generator comprises: a housing made up of first and second cup-shaped brackets 1 and 2; and a stator 3 held between the first and second brackets 1 and 2, which is made up of stator cores 3a and a stator coil 3b wound on the cores 3a. A shaft 6 is rotatably supported by bearings 4 and 5 which are fitted in the central portions of the end walls of the first and second brackets 1 and 2, respectively. Magnetic pole cores 7 and 8 are fixedly mounted on the shaft 6 in such a manner that they are located inside the stator 3. Exciting coils 9 are held between the magnetic pole cores 7 and 8. Fans 10a and 10b are installed on the magnetic pole cores 7 and 8, o respectively, so that they are rotated together with the shaft. Slip rings 11 are mounted on the rear end portion of the shaft 6. The shaft 6, the magnetic cores 7 and 8, the exciting coil 9, the fans 10a and 10b, and the slip rings 11 forms the rotor 12 of the AC generator.
Cooling air sucking holes 1a and cooling air discharging holes 1b are formed in the end wall of the first bracket 1, and similarly cooling air sucking holes 2a and cooling air discharging holes (not shown) are formed in the end wall of the second bracket 2. The outer end portion of the second bracket 2 incorporates: a collector 13 including brushes 13a held in slide contact with the slip rings 11; a rectifier 14; a heat sink 14a for radiating heat generated by the rectifier 14; a voltage regulator 16 which detects a generator voltage to control an exciting current thereby to adjust a terminal voltage to a predetermined value; and a heat sink 16afor radiating heat generated by the voltage regulator 16. When, with exciting current supplied to the exciting coil 9 through the brushes 13a and the slip rings 11, the exciting coil 9 and the magnetic pole cores 7 and 8 are rotated through a pulley 15 by the engine (not shown), AC current is induced in the stator coil 3b. The AC current thus induced is converted into DC current by the rectifier 14. The first and second brackets 1 and 2 are secured through the peripheral portions of the stator cores 3a to each other with bolts 20.
The conventional vehicle's AC generator is constructed as described above. When, with exciting current applied to the exciting coil 9 through the brushes 13a and the slip rings 11, the rotor 12 is rotated through the pulley 15 by the engine (not shown), AC current is induced in the stator coil 3b. The AC current thus induced is rectified by the rectifier 14, the output of which is regulated by the voltage regulator 16. In this operation, the fans 10a and 10b are rotated, so that cooling air is sucked into the generator through the cooling air sucking holes of the first bracket 1 as indicated by the arrows (a) in FIG. 1, thus cooling the bearing 4, the magnetic pole cores 7, the exciting coil 9, the stator cores 3a and the stator coil. Thereafter, the cooling air is discharged through the cooling air discharging holes 1b. At the same time, cooling air is sucked into the generator through the cooling air sucking holes 2a of the second bracket 2, thus cooling the bearing 5, the voltage regulator 16, the rectifier 14, the magnetic pole cores 8, the exciting coil 9, and the stator coil 3b. Thereafter, the cooling air is discharged through the cooling air discharging holes 1b.